Previous HI observations of dSph galaxies

The first claim that HI could be associated with a dSph-like system was for the dIrr/dSph system Phoenix (Carignan, Demers & CУДtУ? 1991). They identified a component, corresponding to , around 50kms^-1, between the Galactic HI kms^-1and gas kms^-1, associated with the Magellanic Stream (MS: Mathewson, Cleary & Murray 1974; Haynes & Roberts 1979). More recently, Young & Lo (1997b) identified another velocity component kms^-1, nearly superposed on the optical.

The other system, in the field of which HI was detected, is the more distant (

kpc) dSph Tucana (Oosterloo, Da Costa & Staveley-Smith 1996). However, since most of the HI is located ( kpc) east of the optical and since the detected gas, if associated with Tucana, would imply a mass in excess of 10⁶, they discarded this possibility and suggested that it was most probably gas associated with the MS. Unfortunately, in both cases, no optical velocities are yet available to disentangle which velocity component could be truly associated with those galaxies.

Т? Copyright Astronomical Society of Australia 1997